Monitoring systems for vehicles fitted with standard tires are in very widespread use. These systems usually warn the driver of the vehicle when the pressure of one of the tires drops below a given threshold relative to the recommended inflation pressures.
For a few years, tire manufacturers have been developing solutions making it possible to run with the same tire, according to certain limits that have to be observed, after a puncture or a drop in pressure. This makes it possible, for example, to get to a repair point without having to stop, in circumstances that are often hazardous, to fit the spare wheel. These tire solutions are known as “extended mobility tires”.
Two broad types of technologies for extended mobility are now emerging on the motor vehicle market. On the one hand, there are self-supporting tires, often designated “zero pressure” (ZP) tires. The self-supporting tires are capable of supporting a load at reduced pressure, even no pressure, thanks to their reinforced side walls, more often than not by means of inserts made of rubbery material provided in the side walls.
On the other hand, there are wheels fitted with supports, capable of supporting the inside of the tread of a tire in the event of a weakening of the side walls following a drop in pressure. This solution is advantageously coupled with a tire comprising a bottom area capable of minimizing the risk of the tire slipping off the rim. This solution is advantageous since it makes it possible to keep the running characteristics substantially intact in normal conditions. On the other hand, it entails the drawback of requiring an additional piece, the support, for each of the wheels of the vehicle.
For all vehicles fitted with extended mobility tires, a pressure monitoring system is mandatory to be able to warn the driver of the vehicle of a loss of pressure and that a tire is beginning to operate in extended mode. The driver then knows that he must limit his speed and that his running autonomy is limited. Some monitoring systems are designed to manage the remaining autonomy.
At the present time, the measuring units usually used in the pressure monitoring systems are not physically attached to the tire itself, but are fixed behind the wheel valves. Thus, after a tire and wheel assembly has been removed, it is no longer possible to guarantee a relationship between the identification code of the measuring unit and the type of tire fitted.
Another problem arises when the driver of the vehicle decides to replace one or more of the extended mobility tires with standard tires. The monitoring system of the extended mobility tires of the vehicle risks no longer being suitable for monitoring standard tires. In such a case, how can the monitoring system be notified of the change of tire type?